The objective of this project are (1) to study the prevalence of human immunodeficiency virus (HIV) infection among persons vulnerable for drug use in an area with relatively low prevalence of reported AIDS cases but with high prevalence of intravenous drug use (IVDU), (2) to evaluate the co-occurrence of behavioral and psychiatric factors, high risk drug use and sexual activity to better target public education efforts aimed at reducing HIV risk behaviors and (3) educate persons who are vulnerable to HIV infection on ways to change these behaviors. Specifically we propose two studies: Study 1 1) Recruit index subjects for a longitudinal study of the prevalence of HIV infection among persons vulnerable to HIV infection. The sample will include persons who are at varying risk such as prisoners, reforming female prostitutes, heroin and other intravenous drug users in methadone, drug free and other treatment, and non-parenteral drug users; 2) Recruit sexual partners to determine (a) HIV seropositivity rates among partners, (b) whether the substance use patterns of sexual partners are to those of the subjects, and (c) whether the psychiatric risk factors of sexual partners are similar to those of the subjects; 3) Evaluate the co- occurrence of the following HIV risk factors: DSM-III, III-R, and ICD-10 substance abuse and dependence, presence and severity of DSM-III and III-R past and current psychiatric symptoms; risk- taking personality traits; high risk sexual behaviors; knowledge of HIV transmission; and sociodemographic factors; 4) Identify (from #3 above) risk factors for, and protective factors against, IVDU and needle sharing; 5) Follow study subjects every twelve months through 04 to determine (a) seroconversion and (b) changes in risk behaviors; 6) Educate persons who are vulnerable to HIV infection on ways to change these behaviors or reduce their risk; 7a) Offer the subjects from this study the opportunity to participate in other Washington University AIDS research; 7b) Cross analyze the data from this proposed study with data to be collected from an eight-year follow-up of a subset of general population subjects (who have not sought treatment but have abused drugs) from the St. louis Epidemiologic Catchment Area (ECA) survey. Study 2 Simultaneously conduct an in-depth longitudinal ethnographic study of needle sharing, high risk sexual behavior, and IV drug use among a subset of Study 1 subjects.